1. Field of the Invention
The present invention relates to the analysis of signal characteristics with the use of masks.
2. Discussion of the Background
If signal characteristics (curve characteristics) of serial data streams are analyzed, for example, with the use of an oscilloscope, it is often necessary to test the signal characteristic against specified mask regions. In this context, the signal characteristic must not contact or not intersect the mask characteristic or the mask, or, in the case of tolerance bands, must not leave the mask region. Typically, such tests are specified within the framework of compliance tests for serial interfaces and data transmission systems.
The mask testing is typically implemented on the basis of the image points, which are stored in an image buffer (display-buffer). The image points can be signal-image points, which are registered through an oscilloscope, converted into image points and stored in the image buffer, as described, for example in EP 677 746 A2. However, if the signal characteristic is composed, for example, of lines, a mask testing of this kind is costly, because every signal-image point must be set and tested individually. Furthermore, in the case of a direct testing, a large memory is required for storing the masks in an image buffer.